docs: def get_indices(self, labels):
          """
          Find the indices of the input ``labels``.
  
          Parameters
          ----------
          labels : int, array-like (1D, int)
              The label numbers(s) to find.
  
          Returns
          -------
          indices : int `~numpy.ndarray`
              An integer array of indices with the same shape as
              ``labels``.  If ``labels`` is a scalar, then the returned
              index will also be a scalar.
  
          Raises
          ------
          ValueError
              If any input ``labels`` are invalid.
          """
  
          self.check_labels(labels)
          return np.searchsorted(self.labels, labels)